J/ApJ/863/89 Gaia DR2 PMs of stars in ultra-faint MW satellites (Simon, 2018)
Gaia proper motions and orbits of the ultra-faint Milky Way satellites.
Simon J.D.
<Astrophys. J., 863, 89 (2018)>
=2018ApJ...863...89S 2018ApJ...863...89S
ADC_Keywords: Galaxies, photometry; Optical; Proper motions
Keywords: astrometry ; dark matter ; galaxies: dwarf ;
galaxies: kinematics and dynamics ; Local Group
Abstract:
The second data release from the Gaia mission (DR2) provides a
comprehensive and unprecedented picture of the motions of astronomical
sources in the plane of the sky, extending from the solar neighborhood
to the outer reaches of the Milky Way. I present proper-motion
measurements based on Gaia DR2 for 17 ultra-faint dwarf galaxies
within 100kpc of the Milky Way. I compile the spectroscopically
confirmed member stars in each dwarf bright enough for Gaia astrometry
from the literature, producing member samples ranging from two stars
in Triangulum II to 68 stars in Bootes I. From the spectroscopic
member catalogs, I estimate the proper motion of each system. I find
good agreement with the proper motions derived by the Gaia
collaboration for Bootes I and Leo I. The tangential velocities for 14
of the 17 dwarfs are determined to better than 50km/s, more than
doubling the sample of such measurements for Milky Way satellite
galaxies. The orbital pericenters are well constrained, with a mean
value of 38kpc. Only one satellite, Tucana III, is on an orbit passing
within 15kpc of the Galactic center, suggesting that the remaining
ultra-faint dwarfs are unlikely to have experienced severe tidal
stripping. As a group, the ultra-faint dwarfs are on high-velocity,
eccentric, retrograde trajectories, with nearly all of them having
space motions exceeding 370km/s. A large majority of the objects are
currently close to the pericenters of their orbits. In a low-mass
(Mvir=0.9x1012M☉) Milky Way potential, eight out of the 17
galaxies lack well-defined apocenters and appear likely to be on their
first infall, indicating that the Milky Way mass may be larger than
previously estimated or that many of the ultra-faint dwarfs are
associated with the Magellanic Clouds. The median eccentricity of the
ultra-faint dwarf orbits is 0.79, similar to the values seen in
numerical simulations but distinct from the rounder orbits of the more
luminous dwarf spheroidals.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 75 17 Ultra-faint dwarf positions, distances, and
velocities
table2.dat 128 1136 Gaia DR2 proper motions of stars
in ultra-faint dwarf galaxies
table3.dat 64 17 Gaia DR2 proper motions and space velocities
table4.dat 60 17 Orbits
refs.dat 61 83 References (table added by CDS)
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/MNRAS/354/708 : Leo I VI photometry (Bellazzini+, 2004)
J/MNRAS/380/281 : Faint galactic satellites spectrosc. survey (Martin+, 2007)
J/MNRAS/397/1748 : Spectroscopic study of Segue 2 (Belokurov+, 2009)
J/ApJ/692/1464 : Spectroscopy of Segue 1 (Geha+, 2009)
J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)
J/ApJS/191/352 : Abundances in stars of MW dwarf satellites (Kirby+, 2010)
J/ApJ/723/1632 : Abundance spreads in Bootes I and Segue 1 (Norris+, 2010)
J/ApJ/711/350 : Metal-poor giant Boo-1137 abundances (Norris+, 2010)
J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)
J/ApJ/741/100 : Proper motions of Leo II member stars (Lepine+, 2011)
J/ApJ/733/46 : Velocity measurements in Segue 1 (Simon+, 2011)
J/ApJ/752/42 : BV time series in Ursa Major II (Dall'Ora+, 2012)
J/ApJ/756/79 : Opt. photom. in 3 Local Group dwarf galaxies (Sand+, 2012)
J/ApJ/767/62 : RR Lyrae stars BV photometry in UMa I (Garofalo+, 2013)
J/ApJ/763/61 : Abundances of 7 Bootees I red giant members (Gilmore+, 2013)
J/ApJ/770/16 : Spectroscopic members of Segue 2 galaxy (Kirby+, 2013)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/ApJ/786/74 : EW measurements of 6 Segue 1 red giants (Frebel+, 2014)
J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)
J/MNRAS/440/2665 : SDSS J021933.13+200830.2 spectroscopy (Roederer+, 2014)
J/AJ/149/42 : Proper motion of Draco dwarf galaxy from HST (Pryor+, 2015)
J/ApJ/808/95 : Spectroscopy of Reticulum II (Simon+, 2015)
J/ApJ/826/110 : Boo-127 and Boo-980 high-resolution spectra (Frebel+, 2016)
J/ApJ/830/93 : Ret II brightest red giant member abundances (Ji+, 2016)
J/ApJ/817/41 : Abundances of 4 metal-poor red giants in BooII (Ji+, 2016)
J/MNRAS/458/L59 : Draco II stars gi magnitudes & RVel. (Martin+, 2016)
J/MNRAS/461/3702 : gi photometry of Bootes I (Roderick+, 2016)
J/AJ/151/82 : 4 brightest red giants in Ret 2 (Roederer+, 2016)
J/ApJ/819/53 : Magellan/M2FS spectroscopy of Tuc 2 & Grus 1 (Walker+, 2016)
J/ApJ/838/44 : Abundances of TucIII brightest members (Hansen+, 2017)
J/ApJ/838/83 : RVel, abundance & membership in TriII (Kirby+, 2017)
J/ApJ/838/11 : Member stars in the MW satellite Tucana III (Simon+, 2017)
J/ApJ/857/74 : Abundances of 7 new member stars in Tucana II (Chiti+, 2018)
J/ApJ/857/145 : MagLiteS Carina II and Carina III spectroscopy (Li+, 2018)
J/ApJ/852/99 : Abundances of 3 metal-poor stars in HorI (Nagasawa+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Dwarf galaxy name
16- 23 F8.4 deg RAdeg Right ascension (J2000)
25- 32 F8.4 deg DEdeg Declination (J2000)
34- 37 F4.1 kpc Dist [21.5/97.3] Distance
39- 42 F4.1 kpc e_Dist [0.4/12] Dist uncertainty
44- 49 F6.1 km/s HRV [-381.7/477.2] Heliocentric radial velocity
51- 53 F3.1 km/s e_HRV [0.4/5.2] HRV uncertainty
55- 57 I3 --- r_Pos [101/131] Position reference (see refs.dat file)
59- 61 I3 --- r_Dist [101/131] Dist reference (see refs.dat file)
63- 65 I3 --- r_HRV [102/132] HRV reference (see refs.dat file)
67- 75 A9 --- Gal Abbreviated galaxy name as in Table 2;
column added by CDS
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- ID Star identifier
23- 31 A9 --- Gal Dwarf galaxy identifier
33- 41 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
43- 51 F9.5 deg DEdeg Declination in decimal degrees (J2000)
53- 57 F5.2 mag gmag [14.6/21.8] Apparent g band AB magnitude
59- 63 F5.2 mag rmag [13.3/20.5] Apparent r band AB magnitude
65- 71 F7.3 mas/yr pmRA [-51/51.6]? Proper motion along RA * cos(DE) (1)
73- 77 F5.3 mas/yr e_pmRA [0.04/1.8]? Uncertainty in pmRA (1)
79- 85 F7.3 mas/yr pmDE [-65.6/20.5]? Proper motion along DE (1)
87- 91 F5.3 mas/yr e_pmDE [0.04/1.3]? Uncertainty in pmDE (1)
93-112 A20 --- Ref Reference codes (see refs.dat file)
114 A1 --- f_ID Spectroscopic member flag on ID (2)
116-128 A13 --- Comm Additional comment
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Note (1): A blank indicates a NaN value.
Note (2): Flag as follows:
1 = spectroscopic member of a dwarf galaxy.
2 = spectroscopic non-member.
Stars previously classified as spectroscopic members but now revealed as
PM non-members should be considered non-members.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Dwarf galaxy name
16- 17 I2 --- Ns [2/68] Number of star members
19- 24 F6.3 mas/yr pmRA [-2.6/3.9] Proper motion along RA * cos(DE)
(µαcosδ)
26- 30 F5.3 mas/yr e_pmRA [0.03/0.4] pmRA uncertainty
32- 37 F6.3 mas/yr pmDE [-3.3/1.6] Proper motion along DE
(µδ)
39- 43 F5.3 mas/yr e_pmDE [0.03/0.4] pmDE uncertainty
45- 50 F6.1 km/s U [-262.3/340] U velocity
52- 57 F6.1 km/s V [-544.8/-119.8] V velocity
59- 64 F6.1 km/s W [-344.8/347.3] W velocity
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Dwarf galaxy name
16- 18 I3 kpc Rper [3/102] Orbital pericenter
20- 21 I2 kpc e_Rper [1/19] Negative uncertainty on Peric
23- 24 I2 kpc E_Rper [1/15] Positive uncertainty on Peric
26- 29 I4 kpc Rapo [49/1746] Orbital apocenter
31- 34 I4 kpc e_Rapo [5/1120] Negative uncertainty on Apoc
36- 39 I4 kpc E_Rapo [6/1654] Positive uncertainty on Apoc
41- 44 F4.2 --- ecc [0.1/1] Orbital eccentricity
46- 49 F4.2 --- e_ecc [0.01/0.5] Negative uncertainty on ecc
51- 54 F4.2 --- E_ecc [0.01/0.7] Positive uncertainty on ecc
56 A1 --- l_Per Limit flag on Per
57- 60 F4.1 Gyr Per [0.7/10]? Orbital period
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Ref Reference code
5- 23 A19 --- BibCode Bibcode of the reference
25- 44 A20 --- Auth First author's name(s)
46- 61 A16 --- Comm VizieR catalogue reference
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Aug-2019